1. Field
Embodiments of the present invention relate to rolling mill laying heads and more particularly to replaceable wear elements for guide ring shrouds in laying heads.
2. Description of the Prior Art
Rolling mill laying heads form moving rolled elongated material into a series of helical continuous loop rings. Those rings may be further processed downstream by bundling them into coils of any desired number of helical turns. Known laying heads are described generally in U.S. Pat. Nos. 5,312,065; 6,769,641; and 7,011,264, the entire contents of all of which are hereby incorporated by reference as if fully contained herein.
As described in these patents rolling mill laying heads include a rotating quill that discharges the elongated material into a radially outwardly flared section, where it is received in the entry end an elongated hollow structure, such as for example a hollow tubular laying pipe. The laying pipe or other elongated hollow structure has a curved intermediate portion that is surrounded by the quill's flared section and an end portion that projects radially outwardly from and generally tangential to the quill's rotational axis. The rotating quill and the laying pipe hollow elongated structure in combination conform the rolled material into a helical curved shape. The laying pipe or other substitute hollow elongated structure may be replaced with one of a different profile and/or diameter in order to reconfigure the laying head to accommodate different dimensioned rolled material.
Further helical profiling of the rolled material is accomplished in a rotating helical guide that includes troughs for receiving the rolled material about its outer circumference. The helical guide described in U.S. Pat. No. 6,769,641 is of segmented, sector-shaped, modular rim construction with the circumferential troughs formed within the rim sectors. When it is desired to reconfigure the laying head to accommodate different dimensioned rolled material all of the rim sectors are changed out with another set having different trough profile and/or helical pitch needed to coil the new material. Whenever a specific trough segment becomes worn in service use, its entire rim sector structural member is replaced with a new one.
A generally annular ring or shroud, also commonly referred to as an end ring or guide ring, has a guide surface that circumscribes the laying pipe discharge end and helical guide, so that the elongated material is confined axially and radially as it is discharged in now fully coiled configuration to a conveyor belt for subsequent bundling and other processing. A pivoting tripper mechanism, including one or more tripper paddles, may be positioned at approximately the six o'clock or bottom position of the end ring/shroud distal the quill. Varying the pivot attack angle of the tripper mechanism relative to the ring/shroud inner diameter surface is useful to control elongated material coiling, for example to compensate for varying elongated material plasticity thickness, composition, rolling speed and cross sectional structure. The tripper paddle top surface is a control surface that is in rubbing contact with the elongated rolled material as it passes through the laying head to the discharge conveyor structure. That rubbing contact in turn causes wear or ablation of the paddle. In the past the tripper mechanism had to be separated from the laying head in order to remove and replace the end ring.
The end ring or shroud needs periodic replacement. Its inner diameter guide surface is also a wear surface that is in rubbing contact with the elongated rolled material as it passes through the laying head to the discharge conveyor structure. The rubbing contact in turn causes wear or ablation of the ring internal guide surface. Often the wear pattern about the end ring is not uniform. Under many circumstances it is found that wear proximal the six o'clock position on the ring and the tripper mechanism is more pronounced than in other circumferential portions of the ring. From a wear resistance point of view it is desirable to form the ring wear surface from relatively hard steel and further desirable to perform further surface hardening and heat treatment, but such wear treatment steps must be balanced with ease and cost of ring fabrication.
The ring/shroud structure often is fabricated from steel sheet that is rolled into a generally annular plan form having a straight cylindrical or frusto-conical, outwardly flaring circumferential walls in the axial dimension. Additional reinforcement flanges, rings and gussets are added to the annular ring. Design trade-offs require compromises between ring material wear resistance properties and fabrication ease/cost. Harder steel grades are generally more difficult to fabricate into rolled annular shapes. Post-fabrication heat treatment and other hardening processes may deform a fabricated end ring. Alternatively, if it is desired to form portions of the end ring with castings, they are more difficult to surface harden than comparable fabricated components.
In the past the only recourse to repair a worn guide end ring/shroud wear surface was to remove and replace the entire end ring with a new one. Excluding the worn wear surface, the remainder of the end ring is otherwise functionally and structurally sound for continued service. Due to the massive end ring structure and how it interoperates with the other laying head components, guide ring replacement is expensive and requires extended laying head downtime during the replacement service operation.